Date of Award
August 2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Engineering
First Advisor
Ryoichi S. Amano
Committee Members
Pradeep K Rohatgi, Ilya V Avdeev, John R Reisel, Priyatha Premnath
Keywords
Dicyclopentadiene (DCPD), Epoxy nanocomposites, Fiber-reinforced polymers (FRPs), Grubbs catalyst, Self-healing wind turbine blades, Vascular networks
Abstract
Wind energy, as a promising renewable resource, offers significant potential for clean, long-term power generation. This research aims to develop wind turbine blades with optimized autonomous self-healing capabilities which lead to reduced maintenance, repair, and energy compensation costs. The approach involves introducing self-healing capabilities into vacuum assisted resin transfer molding (VARTM) molded vascular imprinted fiber-reinforced epoxy composites (FREC), utilizing imprinting vascular networks, three-dimensional (3D) printing templates, infusing with dicyclopentadiene (DCPD), embedding into multilayer FREC, and wetted with first-generation Grubbs catalyst/epoxy mixture. The self-healing mechanism presented in this research utilizes the reaction between DCPD and the catalyst. DCPD is stored as a liquid in the vascular network, isolated from the catalyst until a damaging event triggers their combination. The two agents react and solidify upon damage to form the thermoset polydicyclopentadiene (PDCPD), effectively facilitating recovery from microcracks. This study proposed innovative modifications to these self-healing wind turbine blades to achieve cost-effective higher performance. These modifications include incorporating carbon nanotubes (CNTs) and replacing glass fiber sheets with carbon fiber sheets. This innovative approach enhances the durability and longevity of wind turbine blades, making them more efficient and cost-effective. Wind turbine blades are constantly subjected to bending forces, making self-healing crucial for their longevity. To demonstrate the self-healing capabilities of FREC material, three-point bending and tensile tests were conducted. The samples were tested before and after recovery. The maximum flexural and tensile strengths and percent recovery for the healed and non-healed FREC samples were calculated. Interestingly, in the first part of this study, the synergistic effects of epoxy resin, the PDCPD network, and reinforcement from glass fibers and CNTs result in enhanced mechanical properties for CNTs/DCPD/Glass FREC. Flexural stress (three-point bending) measurements demonstrated that the addition of epoxy resin with 0.6 wt% CNTs to the multilayer FREC to fabricate 0.4wt% CNTs self-healing wind turbine blades yields samples with a high recovery percentage of approximately 201.8%. This enhancement leads to wind turbine blades that are 24.3% stronger in flexural stress for non-healed samples and 27% more efficient in self-healing capabilities for healed samples compared to those without CNTs. Additionally, tensile strength improved by 13.8% for non-healed samples and 24.7% for healed samples, with a 107.9 % recovery percentage. In the second part of the study, the flexural strength of the non-healed DCPD/Hybrid glass-carbon FREC samples exhibited an enhancement by at least 14%, 17.7%, and 10% recorded concurrently with the replacement of glass fiber sheets with one, two, and three carbon fiber sheets. However, the flexural strength of the healed samples increased by at least 14.2%, 15.4%, 8%. At the same time, they showed stress recovery rates of 197.4%, 195%, and 194.3%, respectively. Furthermore, for the case of the replacement of glass fiber sheets with two carbon fiber sheets, the tensile strength improved by 6.9% for non-healed samples and 5.1% for healed samples, with a 96.8 % recovery percentage. Raman spectroscopy was conducted to assess the extent of the reaction between DCPD and the catalyst, resulting in the formation of PDCPD. Microstructure analysis demonstrated the comprehensive healing process in the sample, showing DCPD migration across multiple layers, enhancing the healing efficiency by addressing deeper and more extensive cracks. In the optimization part, the CNTs/DCPD/Hybrid glass-carbon FREC samples showed significant improvement, with 30.7% non-healed stress enhancement and 32.2% healed stress enhancement, with a 200% average recovery, indicating substantial structural enhancements. The tensile strength improved by 19.8% for non-healed samples and 27.1% for healed samples, with a 104.5 % recovery percentage.
Recommended Citation
Saadeh, Walaa Hussein, "OPTIMIZING SELF-HEALING WIND TURBINE BLADES UTILIZING VASCULAR IMPRINTED FIBER-REINFORCED EPOXY NANOCOMPOSITES" (2024). Theses and Dissertations. 3620.
https://dc.uwm.edu/etd/3620